There are a number of prior art couplings which are used for interconnecting various types of fluid conveying lines or conduits. Depending upon the type of fluid to be conveyed, the prior art couplings may be designed to handle special safety requirements. Particularly for conduits which convey fuel, there is always a concern for designing a coupling so that an electrostatic charge does not build up on one of the coupled sections of the line. A stored electrostatic charge may give rise to the hazard of an electrical spark in the presence of vaporized fuel. Discharge of the spark by grounding, or by flexing of the coupling in such a manner to bring metallic parts of the coupling into contact with one another may cause instantaneous combustion of any vaporized fuel which in turn can cause ignition of the fuel conveyed in the lines. Buildup of an electrostatic charge by ionization of fuel as it is conveyed through the fuel lines can be referred to as a static buildup of an electric charge. Lightening strikes can also create a spark, and such strikes are commonly referred to as dynamic causes for creating an electrical charge. Thus, a coupling should also have the capability to dissipate a dynamic electrical charge, such as one caused by a lightening strike. Particularly for lightening strikes, it is important that the coupling have the capability to very quickly dissipate the electrical charge due to the potential magnitude of a spark caused by the lightening strike.
Despite the advances in coupling designs, most fluid conveying lines still utilize metallic flanges which are sealed to the coupling by deformable o-rings. These type of sealing rings may electrically insulate the coupled sections of the line from each other, thus any ionization of fuel that flows through the lines may give rise to a differential electrostatic charge between the coupled sections. Accordingly, there is still a need to ensure electrical conductivity across the coupled sections of the fuel lines to prevent electrostatic buildup.
Various types of electrical jumpers, also known as bonding jumpers, have been used in coupling designs to eliminate the hazard of differential electrostatic charges. A bonding jumper simply provides an electrically conductive connection between the coupled sections of line to prevent buildup of a charge. Two basic types of electrical jumpers include exteriorly and interiorly mounted jumpers. Externally mounted jumpers typically include a piece of flexible metal or cable which is detachably secured to the metallic flanges which are fixed to the adjacent ends of the coupled sections. In many of these prior art exteriorly mounted electrical jumpers, the jumpers themselves require some degree of assembly and disassembly which therefore makes it more difficult to efficiently couple and uncouple the fuel lines.
There are also a number of prior art references which disclose interiorly mounted bonding jumpers. Some of these jumpers are leaf spring types which are mounted within the coupling and placed in contact against the flanges, therefore maintaining electrical conductivity between the flanges of the fluid conveying lines. One particular disadvantage with many types of interiorly mounted bonding jumpers is that there is no means to visually inspect whether the bonding jumpers are properly positioned to make firm contact with the flanges.
Another method of preventing buildup of an electrostatic charge is the use of conductive coatings which may be applied to the coupling assembly and to the flanges of the fluid conveying members. Examples of references disclosing electrically conductive coatings are the U.S. Pat. Nos. 5,786,976 and 5,959,828.
By the foregoing, it is apparent that there still is a need for a coupling assembly which ensures electrical conductivity across adjacent ends of fluid conveying members in a manner which is easy for a user to confirm that the coupling assembly, to include the bonding jumper, is properly installed. Therefore, one of the objects of the present invention is to provide a coupling assembly of a simple yet reliable design which ensures electrical conductivity across the coupling to prevent electrostatic buildup between coupled sections of lines.